The invention provides a pin assembly comprising a pin having a screw threaded portion, a nut having a screw threaded portion, wherein, preferably, the pin has a number of pin recesses and the nut has a splined portion having a number of splines, the assembly further comprising a sleeve having a splined portion having a number of splines and a number of sleeve recesses, and a cross-member for insertion through at least one pin recess, and at least one sleeve recess, such that once assembled, rotation of the nut about the pin axis is restricted by the combination of the mating of the sleeve splined portion with the splined portion of the nut and the insertion of the cross-member through the sleeve recess and pin recess. The invention also provides a fixing assembly, landing gear actuation mechanism, aircraft, method of manufacturing and a kit of parts.